title: ß1 integrin binding phosphorylates ezrin at T567 to activate a lipid raft signalsome driving invadopodia activity and invasion.
abstract: Extracellular matrix (ECM) degradation is a critical process in tumor cell invasion and requires matrix degrading protrusions called invadopodia. The Na(+)/H(+) exchanger (NHE1) has recently been shown to be fundamental in the regulation of invadopodia actin cytoskeleton dynamics and activity. However, the structural link between the invadopodia cytoskeleton and NHE1 is still unknown. A candidate could be ezrin, a linker between the NHE1 and the actin cytoskeleton known to play a pivotal role in invasion and metastasis. However, the mechanistic basis for its role remains unknown. Here, we demonstrate that ezrin phosphorylated at T567 is highly overexpressed in the membrane of human breast tumors and positively associated with invasive growth and HER2 overexpression. Further, in the metastatic cell line, MDA-MB-231, p-ezrin was almost exclusively expressed in invadopodia lipid rafts where it co-localized in a functional complex with NHE1, EGFR, ß1-integrin and phosphorylated-NHERF1. Manipulation by mutation of ezrins T567 phosphorylation state and/or PIP2 binding capacity or of NHE1s binding to ezrin or PIP2 demonstrated that p-ezrin expression and binding to PIP2 are required for invadopodia-mediated ECM degradation and invasion and identified NHE1 as the membrane protein that p-ezrin regulates to induce invadopodia formation and activity.
authors.affiliation: Department of Bioscience, Biotechnology and Biopharmacologics, University of Bari, Bari, Italy ; Department of Pathology, Anatomic Pathology A Unit, Istituto Nazionale Tumori, Milan, Italy.
authors.forename: Ester
authors.initials: E
authors.lastname: Antelmi
authors.forename: Rosa A
authors.initials: RA
authors.lastname: Cardone
authors.forename: Maria R
authors.initials: MR
authors.lastname: Greco
authors.forename: Rosa
authors.initials: R
authors.lastname: Rubino
authors.forename: Francesca
authors.initials: F
authors.lastname: Di Sole
authors.forename: Nicola A
authors.initials: NA
authors.lastname: Martino
authors.forename: Valeria
authors.initials: V
authors.lastname: Casavola
authors.forename: Marialuisa
authors.initials: M
authors.lastname: Carcangiu
authors.forename: Loredana
authors.initials: L
authors.lastname: Moro
authors.forename: Stephan J
authors.initials: SJ
authors.lastname: Reshkin
mesh_terms: D000704:Analysis of Variance; D001943:Breast Neoplasms / Q000378:metabolism*; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D017931:DNA Primers / Q000235:genetics; D005109:Extracellular Matrix / Q000378:metabolism; D005260:Female; D005455:Fluorescent Antibody Technique; D005786:Gene Expression Regulation / Q000235:genetics; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007150:Immunohistochemistry; D047468:Immunoprecipitation; D019012:Integrin beta1 / Q000378:metabolism*; D007558:Italy; D021962:Membrane Microdomains / Q000378:metabolism*; D009361:Neoplasm Invasiveness / Q000503:physiopathology*; D010766:Phosphorylation; D011554:Pseudopodia / Q000502:physiology*; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D000099149:Ezrin
chemical_list: D003598:Cytoskeletal Proteins; D017931:DNA Primers; D019012:Integrin beta1; D018719:Erb-b2 Receptor Tyrosine Kinases; D000099149:Ezrin; C508053:ERBB2 protein, human